1. Field of the Invention
This invention relates to the field of arming safety systems and methods.
2. Description of the Related Art
In arming weapons systems, it is required that two independent logic elements are utilized to control weapon arming safety, such as for a missile warhead. One of the logic elements may involve sending a signal upon the occurrence of one or more launch events. Examples of launch events include the disconnection of an umbilical connection between a missile and a launching aircraft, pull of a lanyard on the weapon, sending of an ignition signal, and pressure in the base of the missile.
The other logic element may involve sending a signal upon the occurrence of one or more flight events. Examples of such flight events include sustained flight acceleration, eject shock, a launch pulse, spinning of the missile, turning of a wind turbine on the weapon or missile, elevated pressure in a pitot-static tube, actuation of a wing/fin switch, and detection of a weapon arming maneuver (WAM).
The launch events and the flight events collectively constitute a group of logic events. In an arming system, as each successive logic event is satisfied (reaches a “true” value), the associated safety locks of the system are successively removed. Eventually the system is reduced to one remaining safety lock that prevents arming. This is a single-point failure condition, wherein a failure of the single remaining safety lock would result in undesired arming of the weapon, perhaps resulting in premature detonation.
Despite the problems that might result from premature arming or detonation of a weapon, the existence of a single-point failure mode is presently tolerated in current missile systems. The risk is reduced somewhat by attempts to minimize the amount of time in which a single-point failure would result in arming or detonation.
From the foregoing it will be appreciated that there is room for possible improvement in arming systems for missiles and other weapons.